Method of making metal impressions



May 8 1928.

H SWAN METHOD OF MAKING METAL IMPRESSIONS Filed Sept. 10,

Patented May 8, 1928.

UNITED STATES PATENT OFFICE. I

HYLTON SWAN, F UPPER HONTCLAIR, NEW JERSEY, ASSIGNOB TO BAKELI'TE COB- POBATION, OF NEW YORK, N. Y.,

A CORPORATION OF DELAWARE.

kernel) or MAKING METAL rmrnnssrons Application filed September 10, 1925. Serial No. 55,556.

' This .invention relates to the art of printing, and in particular ,to negatives made made from a type set-up, an engraving, an elcctrotype, or other positive. Such negatives are commonly made by pressing directly, as by means of the platen of a hydraulic or other press, a sheet of soft metal such as lead or lead alloy upon the type with sufiicient force so that the lead flows into the interstices of the type and retains and mpression thereof. As this method is-"employed at present a pressure of 4- or fit'ons per square inch may he required and such a pressure may crush, mar or deface the type. rendering it unfit or inferior for reproduction. I have now found that if fluid pressure be applied to the soft metal sheet the latter is, as it were, wrapped about the projecting type face and enters into the interstices thereof, giving a sharp and clear negative. This may be accomplished at fluid-pressures which do not injure the type and which may be in some instances of the order of 2000 lbs. per square inch.

M invention as applied to the production of a negative from a set of type may be carried out in the manner shown in the accompanying drawing,-in which the figure is a central, vertical section through a die suitable for makinga lead impression or negative. In thegfigure, 1 is the body of the steel die or mold of which the upper platen or closure plate is shown at .2. The opening within the die is provided with shoulders? upon which is placed a lead sheet 4 in which the type impression is to be made. Above this lead plate is placed a printers chase 5 in which the type may be set up and locked in the usual manner, the type face being shown at 9. The die is then closed by the steel plate 2 described above. An inlet passage 6 is provided in the die whereby fluid under pressure may be admitted to the chamber 7. A knockout piece 8 is also provided, to be used as later described. 1

It, now, a fluid under suitable pressure is admitted through the inlet 6 to the chamber 7 the pressure will be applied to the lead sheet 4 and will force this sheet against the.

type face 9. Since this fluid pressure is the same in all directions the lead sheet will be wrapped closely. about the projections, and will be forced into the interstices, giving a sharp negative. As stated above, I have 5 succeeded in producing this result with fluid pressures which do not injure thetype. and whichmay be of the order of 2000 lbs. per square inch.

To exert the fluid pressure, I may employ any suitable liquid such as water or oil. I have found, however, that there are considerable advantages in using an alloy which melts, and is introduced in a molten state, at a temperature below the melting point of the lead sheet. This molten alloy may be introduced into the chamber 7 under the de sired pressure. The supply is then shut off and the portion of the alloy within the chamber is permitted to cool. It thus forms a backing for the lead sheet, which would otherwise have to be backed up in a separate operation. The sheet upon which the type impression is made need not of course be of lead, but may be composed of any suitable metal or alloy. It may, if desired, have in its composition or applied to its face a flux or suitable agent to cause this molten alloy to unite therewith. \Vhen the pressure is supplied by means of a molten al'loy which provides a backing for the lead plate. it may be necessary to use the knockout block 8 in order to remove the cooled alloy from the die.

The original or positive may of course be 5 reproduced from the lead impression in any desired manner, as for instance, by moldingwax or other plastic composition into the impression, or by electrotyping, or any other known method.

My invention is not limited to taking ofl impressions from type, but may apply to any positive or original such as an engraving, elec-trotype, wood cut, or any relief or intaglio. I employ the word positive as a 5 generic term covering all such objects of which an impression may be desired.

I claim:

1. The method of making an impression from a positive which comprises forcmg a 100 metal sheet against the positive by means of molten metal under pressure, said molten metal having a melting point lower than that of said metal sheet, and allowing said molten metal to solidify in the form of a backing for saidmc-tal sheet.

2. The method of simultaneously making and backing up a soft 'meta'l impression which comprises forcing a sheet of soft metal 10 against a positive by means of the fluid presimpressions, said sheet comprising lead and 15 a flux whereby a molten backing alloy is caused to unite therewith.

In testimony whereof, I aflix my slgnature.

- HYLTON SlVAN. 

